This Quality Assurance/Quality Control Compendium (QA/QC Compendium) has been prepared by the Intergovernmental Data Quality Task Force (IDQTF) to supplement Part 1 of the Uniform Federal Policy for Quality Assurance Project Plans (the UFP-QAPP Manual). The UFP-QAPP Manual and the QA/QC Compendium along with the UFP-QAPP Workbook and Example QAPPs, serve as companion documents to the IDQTF's Uniform Federal Policy for Implementing Environmental Quality Systems (UFP-QS). The UFP-QS and the UFP-QAPP were developed as consensus initiatives by the U.S. Environmental Protection Agency (EPA), the Department of Defense (DoD), and the Department of Energy (DOE). The purpose of the UFP-QAPP is to serve as a single national consensus document for consistent and systematic implementation of project specific guidelines per Section 6 (Part B) of ANSI/ASQ E4 (Quality Systems for Environmental Data and Technology Programs - - Requirements with guidance for use). The purpose of this QA/QC Compendium is to establish minimum specifications for data quality activities for all phases and data uses in the CERCLA process.